Yakovlev Yak-3 (II)
This entry relates to the second generation Yak-3. For the Yak-1 derivative designated Yak-3, visit the Yakovlev Yak-3 (I-30) entry. The Yakovlev Yak-3 (II), commonly known as the Yak-3, was a russian interceptor aircraft of world War 2. Description Early in 1941, the Yak-3 was conceived to meet a specific V-VS requirement for an exceptionally agile single-seat ﬁghter capable of maximum performance at low altitude, and suitable for maintenance of aerial superiority in the immediate vicinity of the battlefield. The Yak-3 appeared in V-VS service in the summer of 1944 as the smallest and lightest warplane in its category to see large-scale operational service during World War II. Originally intended to use the M-107 engine, the Yak-3 — the designation being re-assigned from the defunct I-30 programme (which see) — was developed via a modiﬁed Yak-1M which, ﬁtted with a smaller wing, was ﬂown late in 1942. Further reﬁnement of the aircraft undertaken by Konstantin V Sinelshchikov led to the oil cooler air intake sharing wing root positioning with those for the carburettor and supercharger. Non-availability of the M-107A engine led to adoption of the M-105PF-2, which, operating at higher revs than the PF-1 version in the Yak-1M, afforded 1,300 hp at 2,625 ft (800 m). Armament consisted of one engine-mounted 20-mm ShVAK cannon and two 12,7-mm UBS machine guns. The development programme was delayed when the prototype Yak-3 suffered a structural failure, full State Acceptance trials not being completed until October 1943, by which time a small pre-series was under construction at GAZ 286 at Kamensk Ural’ski. These were immediately assigned on completion to an operational regiment for service trials, and, in the event, saw combat during the Soviet counter-offensive to Operation Zitadelle. Despite the success of these combat trials, the Yak-3 was not officially cleared by the NII V-VS for production until June 1944, but the 91 IAP had re-equipped with this type by July, and, on the 16th of that month, was able to claim destruction of 24 Bf 109Gs and Fw 190s in one low-altitude melee involving 18 of the IAP’s Yak-3s. Virtually simultaneously, the French Normandie-Niémen regiment began re-equipping with the Yak-3. The basic Yak-3 was the subject of considerable experimentation, test variants including the Yak-3RD ﬁtted with a so-called “auxiliary accelerator" in the form of a Glushko RD-1 (KhZ) bi-fuel (nitric acid and kerosene) rocket motor in the tail. A speed of 498 mph (801 km/h) was attained with the aid of this rocket while in a shallow climb, but on 16 August 1944, the Yak-3RD was lost when the rocket exploded. Second-generation Yak-3s were evolved with M-107 and M-108 engines see), but these were not to achieve large-scale production, contributing comparatively few to the total of 4,848 of this ﬁghter that had been delivered when production ended at the beginning of 1946. Max speed, 367 mph (590 km/11) at sea level, 407mp11 (655 km/h) at 10,170ft (3 100 m). Initial climb, 3,800 ft/min (19, 30m/sec). Max range, 56011115 (9001cm). Empty weight, 4,641 lb (2 105 kg). Loaded Weight, 5,6221b (2 550 kg). Span, 30ft.2% in (9,20 m). Length, 27ft10% in (8,49 m). Height, 7ft 11%; in (2,42 m). Wing area, 159.63 sqft (14,193 mg). Page 603 Variants Yakovlev Yak-3M-107 In parallel with second-generation [[Yavovlev Yak-9|Yak-9] development using the M-107 engine, the Yakovlev OKB undertook similar development of the basic Yak-3. The ﬁrst M-107A-powered Yak-3 — referred to simply as the Yak-3M-107 — was ﬂown in the late autumn of 1943, the ﬁghter having been intended for this engine from the outset. At this time, work was proceeding on the redesign of the airframe for light alloy stressed-skin construction, and the all-metal Yak-3 with the M-107A engine was to undergo State Acceptance tests between February and May 1945, demonstrating a spectacular performance. The nose was marginally lengthened, the cockpit was repositioned 12.6 in (32 cm) aft for cc reasons and a deeper radiator bath was adopted. The M-107A engine was rated at 1,650 hp for take-off and armament remained similar to that of the ﬁrst-generation Yak-3, comprising two synchronised 12,7-mm UBS machine guns and one 20-mm engine-mounted ShVAK cannon. The ofﬁcial report following completion of State Acceptance tests stated: “The experimental Yak-3 powered by the M-107A . . . ..appears to offer the best performance of all indigenous and known foreign ﬁghters." Nonetheless, the Yak-3M-107 was too late for large scale production, only a limited series being built, including a number with revised armament under the designation Yak-3P — pushka, or “cannon” armed. This comprised two synchronised 20-mm B-20 cannon and a third ﬁring through the propeller hub. An anti-armour version, the Yak-3T — tyazhely, or "heavy" cannon — was similar but had the engine-mounted B-20 replaced with a 37-mm NS—37, and one example (ﬂown only once) was ﬁtted with a 57-mm engine-mounted OKB-16-57 cannon. Known unofficially to the few V-VS regiments that equipped with the Yak-3M-107 during 1945-46 as the Ubiytsa (Killer) — an appellation reﬂecting its predatory capabilities rather than any malicious intent towards its pilot — it was alleged to have been the fastest piston-engined ﬁghter to have attained service status. Max speed, 386 mph (622 km/h) at 1,640 ft (500 m), 477mph (720 km/I1) at 18,045 ft (5 500m). Time to 16,405ft (5,000 m), 3.9 min. Loaded weight, 6,578 lb (2 984 kg). Dimensions as for standard Yak-3 apart from overall length of 29 ft 1 1/4 in (8.87m). Yakovlev Yak-3M-108 Destined to be the fastest of all piston-engined Yakovlev ﬁghters, the Yak-3M-108 possessed a similar all-metal airframe to the deﬁnitive Yak-3M~107 from which it differed only in engine and armament. With the availability of the Klimov M-108 12-cylinder Vee-type engine rated at 1,850 hp, the Yakovlev OKB initiated adaptation of an airframe to take this power plant in August 1944. The aircraft was rolled out on 7 October that year, and the ﬁrst two ﬂights were effected on 19 December. Armament consisted of a single engine-mounted 23-mm NS-23 cannon, and, on 21 December, thisYak-3M-108 recorded a speed of 463 mph (745 km/h) at 19,685 ft (6 O00 m) and climbed to 16,405 ft (5 O00 m) in 5 min. Yakovlev subsequently claimed the speed attained on that occasion to be the highest ever achieved in level ﬂight by a Soviet piston-engined aircraft. The M-108 engine presented numerous development problems, inhibiting the ﬂight test programme until, in January 1945, further work on the power plant and prototype was cancelled. Max speed, 388 mph (625 km/11) at sea level, 463 mph (745 kmﬂi) at 19,685 ft (6 000 in). Loaded weight, 6,239lb (2 830 kg). Dimensions as for Yak-3M-107. Yakovlev Yak-3U The last piston-engined ﬁghter to be produced by the Yakovlev OKB, the Yak-3U — Uluchshennyi, or “improved” — bore no relationship to the bureau’s earlier radial-engined single-seater, the Yak-7M~82, other than its common design origin. Retaining the light alloy stressed-skin metal wing and tail surfaces of the second-generation M-107A-engined Yak-3, it mated these elements with an entirely new fuselage and an M-82FN (ASh-82FN) 14-cylinder two-row radial rated at 1,850 hp. The engine was extremely close cowled, careful attention was given to the hermetic sealing of the fuselage and power loading was reduced to 3.351b/hp (1.5 kg/cv) from the 4.02 lb/hp (1.8 kg/cv) of the M-107A-engined ﬁghter. Armament consisted of twin synchronised 20-mm B-20 cannon, but these were interchangeable with paired 23-mm NS-23 guns. The Yak-3U was developed under a comparatively low-priority programme and was not ﬂown until 12 May 1945. During its test programme it proved outstandingly manoeuvrable — it was claimed by the test team to be more agile than any known ﬁghter - but, being considered conceptually obsolescent, the Yak-3U was not subjected to State Acceptance testing, and only the one prototype was completed. * Max speed, 385 mph (620 km/h) at sea level, 441 mph (710 km/11) at 20,015 ft (6 100 m). * Time to 16,405 ft (5 000 m), 3.8 min. * Range, 441 mls (710 km). * Loaded weight 6,151 lb (2,790 kg) * Span 30 ft 10 in (9.40 m) * Length 27 ft 5 1/8 in (8.36 m) References Category:Russian Category:World War 2